Electrically operated aerosol-generating system with tilt sensor

ABSTRACT

An electrically operated aerosol-generating system for receiving a liquid aerosol-forming substrate and a main unit and a cartridge for an electrically operated aerosol-generating system. The aerosol-generating system includes a liquid storage portion configured to hold a liquid aerosol-forming substrate; an aerosol generator configured to receive liquid aerosol-forming substrate from the liquid storage portion; one or more capillary wicks configured to transfer liquid aerosol-forming substrate from the liquid storage portion to the aerosol generator; a tilt sensor configured to sense the orientation of the liquid storage portion; and electric circuitry. The electric circuitry is configured to monitor the orientation of the liquid storage portion as sensed by the tilt sensor and determine depletion of liquid aerosol-forming substrate based on the orientation of the liquid storage portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to,international application no. PCT/EP2017/053707, filed on Feb. 17, 2017,and further claims priority under 35 U.S.C. §119 to European PatentApplication No. 16157434.8, filed Feb. 25, 2016, the entire contents ofeach of which are incorporated herein by reference.

BACKGROUND

Some example embodiments relate to an electrically operatedaerosol-generating system.

Electrically operated aerosol-generating systems that atomise a liquidsubstrate typically comprise a device portion, comprising a battery andcontrol electronics, and a cartridge portion, comprising a supply ofaerosol-forming substrate and an electrically operated atomiser. Acartridge comprising both a supply of aerosol-forming substrate and anatomiser is sometimes referred to as a ‘cartomizer’. The atomiser istypically a heater assembly. In some known examples, the aerosol-formingsubstrate is a liquid aerosol-forming substrate and the atomisercomprises a coil of heater wire wound around an elongate wick soaked inliquid aerosol-forming substrate. The cartridge portion typically alsocomprises a mouthpiece. Other arrangements of electrically operatedaerosol-generating systems are also possible. For example, anaerosol-generating system may comprise three parts, a main unitcomprising a battery and control electronics, a cartridge portioncomprising a supply of aerosol-forming substrate, and an electricallyoperated atomiser portion comprising an atomiser. Both the cartridgeportion and the atomiser portion may be disposable.

Electrically operated aerosol generating systems may be configured toperform other functions, such as providing an indication of thedepletion of liquid aerosol-forming substrate and the amount of liquidaerosol-forming substrate remaining in the liquid storage portion. Forexample, WO2012085203A1 describes an electrically operatedaerosol-generating system comprising electric circuitry configured todetermine depletion of liquid aerosol-forming substrate based on arelationship between a power applied to a heating element and aresulting temperature change of the heating element. Determination ofdepletion is advantageous for a number of reasons. For example, when theliquid storage portion is empty or nearly empty, insufficient liquidaerosol-forming substrate may be supplied to the electric heater. Thismay mean that the generated aerosol does not have the desiredproperties, for example, aerosol particle size or chemical composition.This may result in a poor experience. In addition, if it can bedetermined when the liquid storage portion is empty or nearly empty, itmay be possible to inform an operator, so that the operator can prepareto replace or refill the liquid storage portion.

It would be desirable for a determination of depletion of liquidaerosol-forming substrate by an electrically operated aerosol-generatingsystem to be as accurate as possible.

SUMMARY

At least one embodiment relates to an electrically operatedaerosol-generating system for receiving a liquid aerosol-formingsubstrate.

In one embodiment, the aerosol-generating system includes a liquidstorage portion configured to hold a liquid aerosol-forming substrate;an aerosol generator configured to receive liquid aerosol-formingsubstrate from the liquid storage portion; one or more capillary wicksconfigured to transfer liquid aerosol-forming substrate from the liquidstorage portion to the aerosol generator; a tilt sensor configured tosense the orientation of the liquid storage portion; and electriccircuitry configured to monitor the orientation of the liquid storageportion as sensed by the tilt sensor and determine depletion of liquidaerosol-forming substrate based on the orientation of the liquid storageportion.

Other embodiments relate to a cartridge of an aerosol-generating system,a main unit of an aerosol-generating system, or other elements of anaerosol-generating system.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described in detail, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a first embodiment of anelectrically operated aerosol-generating system; and

FIG. 2 is a schematic illustration of a second embodiment of anelectrically operated aerosol-generating system.

DETAILED DESCRIPTION

Example embodiments will become more readily understood by reference tothe following detailed description of the accompanying drawings. Exampleembodiments may, however, be embodied in many different forms and shouldnot be construed as being limited to the example embodiments set forthherein. Rather, these example embodiments are provided so that thisdisclosure will be thorough and complete. Like reference numerals referto like elements throughout the specification.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises,” “comprising,”“includes,” and/or “including,” when used in this specification, specifythe presence of stated features, integers, steps, operations, and/orelements, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, and/or groupsthereof.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on”, “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, regions, layers and/orsections, these elements, regions, layers and/or sections should not belimited by these terms. These terms are only used to distinguish oneelement, region, layer or section from another region, layer or section.Thus, a first element, region, layer or section discussed below could betermed a second element, region, layer or section without departing fromthe teachings set forth herein.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in operation in addition to the orientationdepicted in the figures. For example, if the device in the figures isturned over, elements described as “below” or “beneath” other elementsor features would then be oriented “above” the other elements orfeatures. Thus, the example term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Some example embodiments are described herein with reference tocross-section illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures). As such, variationsfrom the shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, are to be expected. Thus,these example embodiments should not be construed as limited to theparticular shapes of regions illustrated herein, but are to includedeviations in shapes that result, for example, from manufacturing.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and this specification and will not beinterpreted in an idealized or overly formal sense unless expressly sodefined herein.

Unless specifically stated otherwise, or as is apparent from thediscussion, terms such as “processing” or “computing” or “calculating”or “determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical, electronicquantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission or display devices.

As disclosed herein, the term “storage medium”, “computer readablestorage medium” or “non-transitory computer readable storage medium,”may represent one or more devices for storing data, including read onlymemory (ROM), random access memory (RAM), magnetic RAM, core memory,magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other tangible machine readable mediums for storinginformation. The term “computer-readable medium” may include, but is notlimited to, portable or fixed storage devices, optical storage devices,and various other mediums capable of storing, containing or carryinginstruction(s) and/or data.

Furthermore, at least some portions of example embodiments may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware or microcode, the programcode or code segments to perform the necessary tasks may be stored in amachine or computer readable medium such as a computer readable storagemedium. When implemented in software, processor(s), processingcircuit(s), or processing unit(s) may be programmed to perform thenecessary tasks, thereby being transformed into special purposeprocessor(s) or computer(s).

When the terms “about” or “substantially” are used in this specificationin connection with a numerical value, it is intended that the associatednumerical value include a tolerance of ±10% around the stated numericalvalue. Moreover, when reference is made to percentages in thisspecification, it is intended that those percentages are based onweight, i.e., weight percentages. The expression “up to” includesamounts of zero to the expressed upper limit and all values therebetween. When ranges are specified, the range includes all values therebetween such as increments of 0.1%. Moreover, when the words “generally”and “substantially” are used in connection with geometric shapes, it isintended that precision of the geometric shape is not required but thatlatitude for the shape is within the scope of the disclosure. Althoughthe tubular elements of the embodiments may be cylindrical, othertubular cross-sectional forms are contemplated, such as square,rectangular, oval, triangular and others.

In one embodiment, there is provided an electrically operatedaerosol-generating system for receiving a liquid aerosol-formingsubstrate. The aerosol-generating system comprises a liquid storageportion configured to hold a liquid aerosol-forming substrate and anaerosol generator arranged to receive liquid aerosol-forming substratefrom the liquid storage portion. One or more capillary wicks arearranged to transfer liquid aerosol-forming substrate from the liquidstorage portion to the aerosol generator. A tilt sensor is arranged tosense the orientation of the liquid storage portion. Electric circuitryis configured to monitor the orientation of the liquid storage portionas sensed by the tilt sensor and determine depletion of liquidaerosol-forming substrate based on the orientation of the liquid storageportion. The electric circuitry may include a processor and a memory, anapplication specific integrated circuit (ASIC), or combination thereof.The memory may be a nonvolatile memory, such as a flash memory, aphase-change random access memory (PRAM), a magneto-resistive RAM(MRAM), a resistive RAM (ReRAM), or a ferro-electric RAM (FRAM), or avolatile memory, such as a static RAM (SRAM), a dynamic RAM (DRAM), or asynchronous DRAM (SDRAM). The processor may be a central processing unit(CPU) or a controller that when executing instructions stored in thememory, configures the processor as a special purpose computer toperform the operations of the electric circuitry.

In use of the electrically operated aerosol-generating system, liquidaerosol-forming substrate is drawn through the one or more capillarywicks by capillary action. Liquid aerosol-forming substrate in the oneor more capillary wicks is received at the aerosol generator. When theaerosol generator is activated, the liquid aerosol-forming substratereceived at the aerosol generator is atomised by the aerosol generatorand is drawn away from the liquid storage portion via an airflow throughthe aerosol generating system. This depletes the amount of liquidaerosol-forming substrate held in the liquid storage portion.

During normal use, when sufficient liquid aerosol-forming substrate isheld in the liquid storage portion, the capillary properties of the oneor more capillary wicks and the properties of the liquid aerosol-formingsubstrate ensure that the one or more capillary wicks are regularlydrawing liquid aerosol-forming substrate from the liquid storage portionto the aerosol generator. The rate at which the liquid aerosol-formingsubstrate is drawn along the one or more capillary wicks is known as thewicking rate, or the rate of imbibition. The wicking rate may bedependent on the properties of the liquid aerosol-forming substrate,such as the viscosity of the liquid aerosol-forming substrate. In otherwords, the wicking rate may be affected by gravity. The wicking rate mayalso be dependent on the orientation of the one or more capillary wicks.For example, the wicking rate of a liquid aerosol-forming substratedrawn upwards through an upright capillary wick, may be lower than thewicking rate of the liquid aerosol-forming substrate drawn downwardsthrough an inverted capillary wick.

Depletion of liquid aerosol-forming substrate from the liquid storageportion may depend on the wicking rate and the orientation of the one ormore capillary wicks. For example, in use, when the aerosol generator isactivated, liquid aerosol-forming substrate drawn downwards through aninverted capillary wick may be received at the aerosol generator at afaster rate than liquid aerosol-forming substrate drawn upwards throughan upright capillary wick. This may result in a larger amount of theliquid aerosol-forming substrate being received at the aerosol generatorduring a period of activation when the one or more capillary wicks areinverted. This may result in a larger amount of liquid aerosol-formingsubstrate being depleted from the liquid storage portion during a periodof activation of the aerosol generator when the one or more capillarywicks are inverted, compared to when the one or more capillary wicks areupright.

As used herein, the one or more capillary wicks are described asinverted when the one or more capillary wicks are arranged to drawliquid aerosol forming substrate downwards, and the one or morecapillary wicks are described as upright when the one or more capillarywicks are arranged to draw liquid aerosol-forming substrate upwards.Downwards is used to describe motion in a direction with the force ofgravity and upwards is used to describe motion in a direction againstthe force of gravity.

The orientation of the one or more capillary wicks may depend on theorientation of the liquid storage portion. Therefore, variations in theorientation of the liquid storage portion may result in variations inthe depletion of liquid aerosol-forming substrate from the liquidstorage portion. As used herein, the orientation of the liquid storageportion and the orientation of the one or more capillary wicks are usedinterchangeably. In other words, the liquid storage portion is describedas inverted when the one or more capillary wicks are inverted and theliquid storage portion is described as upright when the one or morecapillary wicks are upright.

The electric circuitry is configured to determine depletion of liquidaerosol-forming substrate from the liquid storage portion based onmeasurements of the orientation of the liquid storage portion. In otherwords, the electric circuitry is configured to compensate or adjust adetermination of depletion of liquid aerosol-forming substrate from theliquid storage portion to account for variations in the orientation ofthe liquid storage portion. This orientation compensation or adjustmentmay improve the accuracy of the determination of depletion of liquidaerosol-forming substrate for the liquid storage portion. This mayimprove the experience for an operator. For example, a more accuratedetermination of depletion may enable the electric circuitry to indicatethat the liquid storage portion requires replacement or refilling whenthe determined amount of liquid aerosol-forming substrate remaining islower. This may reduce wastage of liquid aerosol-forming substrate andreduce the cost of using the aerosol-generating system.

As used herein, depletion or consumption of liquid aerosol-formingsubstrate from the liquid storage portion may refer to an amount ofliquid aerosol-forming substrate that has been removed from the liquidstorage portion. The determined amount of liquid aerosol-formingsubstrate depleted from the liquid storage portion may be an absoluteamount or a relative amount, such as a percentage value. Depletion orconsumption may also refer to a rate of depletion of liquidaerosol-forming substrate held in the liquid storage portion. A rate ofdepletion may comprise a reduction in the amount of liquidaerosol-forming substrate held in the liquid storage portion over aperiod of time.

The electric circuitry may also be configured to determine the amount ofliquid aerosol-forming substrate remaining in the liquid storage portionbased on the determined depletion. The electric circuitry may also beconfigured to determine the time remaining or the number of puffsremaining until the liquid aerosol-forming substrate held in the liquidstorage portion is depleted or exhausted based on the determineddepletion. The liquid aerosol-forming substrate may be considered to bedepleted or exhausted from the liquid storage portion when the amount ofliquid aerosol-forming substrate held in the liquid storage portion isreduced below a desired (or, alternatively predetermined) threshold.

The tilt sensor may be any suitable type of tilt sensor or inclinometerfor sensing the orientation of the liquid storage portion. The tiltsensor may be an accelerometer. Suitable types of tilt sensor include,amongst others, MEMs sensors, rolling-ball sensors, force balancesensors, electrolytic sensors and capacitive tilt sensors.

The tilt sensor may be arranged at any suitable location relative to theliquid storage portion for sensing the orientation of the liquid storageportion.

The tilt sensor may be arranged in the liquid storage portion. When thetilt sensor is arranged in the liquid storage portion, the tilt sensormay be coated with a fluid impermeable coating or surrounded by a fluidimpermeable housing to protect the tilt sensor from contact with theliquid aerosol-forming substrate.

The tilt sensor may be arranged adjacent to the liquid storage portion.This may reduce the cost of the tilt sensor compared to a tilt sensorarranged inside the liquid storage portion, because a tilt sensorarranged adjacent to the liquid storage portion may not requireadditional protection from contact with the liquid aerosol-formingsubstrate.

The aerosol-generating system may comprise a plurality of removablycouplable elements. For example, the aerosol-generating system maycomprise a cartridge comprising the liquid storage portion and a mainunit comprising the electric circuitry. The tilt sensor may be arrangedin any of the removably couplable elements. The tilt sensor may bearranged in the main unit or in the cartridge. The main unit may beconfigured for multiple uses. The cartridge may be configured for asingle use and may be disposable. It may be advantageous to arrange thetilt sensor in the main unit, such that the tilt sensor is not disposedof with the cartridge after a single use of the aerosol-generatingsystem. This may reduce the cost of the cartridges.

The electric circuitry may comprise any suitable elements. The electriccircuitry may comprise a microprocessor. The microprocessor may be aprogrammable microprocessor.

The electric circuitry may comprise a memory. The memory may store alookup table. The lookup table may comprise stored reference orientationinformation. The lookup table may comprise stored liquid aerosol-formingsubstrate depletion information. The stored depletion information maycomprise information relating to the amount of liquid aerosol-formingsubstrate depleted from the liquid storage portion or may compriseinformation relating to the rate of depletion of liquid aerosol-formingsubstrate from the liquid storage portion. The stored referenceorientation information may be associated with the stored depletioninformation in the lookup table.

The electric circuitry may be configured to compare measurements oforientation of the liquid storage portion from the tilt sensor with thestored reference orientation information in the lookup table. Theelectric circuitry may be configured to associate the measurements oforientation with the stored liquid aerosol-forming substrate depletioninformation. The electric circuitry may be configured to determine anestimate of depletion of liquid aerosol-forming substrate from theliquid storage portion based on the comparison.

The electric circuitry may be configured to determine a first estimateof depletion of liquid aerosol-forming substrate based on measurementsof one or more quantities of the aerosol-generating system, such asmeasurements of the power supplied to the aerosol generator. Theelectric circuitry may be further configured to determine a secondestimate of depletion based on the first determined estimate ofdepletion and measurements of the orientation of the liquidaerosol-forming substrate held in the liquid storage portion. This mayimprove the first determined estimate of depletion.

The depletion information stored in the lookup table may comprise anumerical value which may be used as a multiplier or a factor foradjusting the first estimate to compensate for variations in theorientation of the liquid storage portion. The electric circuitry may beconfigured to compare measurements of orientation of the liquid storageportion with reference orientation information stored in the lookuptable. The electric circuitry may be configured to associate themeasurements of orientation of the liquid aerosol-forming substrate heldin the liquid storage portion with the stored depletion informationmultipliers or factors based on the comparison. The electric circuitrymay be configured to determine the second estimate of depletion based onthe first estimate of depletion and the multiplier or factor stored inthe lookup table associated with the reference orientation informationmatched with the measured orientation information. The electricalcircuitry may be configured to determine the second estimate ofdepletion based on the product of the first estimate of depletion andthe multiplier or factor associated with the measured liquidaerosol-forming substrate orientation information.

The reference orientation information stored in the lookup table and thedepletion information stored in the lookup table may be determined in acalibration procedure. For example, the liquid storage portion may befilled with a known liquid aerosol-forming substrate, the liquid storageportion may be held at a known orientation and a known regime may beperformed to deplete the liquid aerosol-forming substrate from theliquid storage portion. The amount of liquid aerosol-forming substrateheld in the liquid storage portion may be measured periodically and thedepletion may be calculated. The calculated depletion may be stored inthe lookup table and associated with the known orientation information.This process may be repeated for a variety of liquid storage portionorientations. The calibration procedure may be performed before firstuse of the aerosol-generating system by an operator, for example, by themanufacturer at the factory.

The electrical circuitry may be configured to calculate the depletionbased on measurements of the orientation of the liquid storage portion.The electrical circuitry may be configured to calculate an estimate ofthe depletion based on the dimensions and properties of the one or morecapillary wicks, the fluid properties of the liquid aerosol-formingsubstrate and measurements of the orientation of the liquid storageportion.

For example, the orientation of the liquid storage portion may beconsidered to be the angle between the longitudinal axis of the liquidstorage portion and the vertical axis with respect to ground or gravity.In other words, the angle between the longitudinal axis of the liquidstorage portion and the vertical axis may be 0° when the liquid storageportion is inverted, 180° when the liquid storage portion is upright and90° or 270° when the liquid storage portion is horizontal. The depletionof liquid aerosol-forming substrate from the liquid storage portion maybe proportional to the cosine of the angle between the longitudinal axisof the liquid storage portion. As such, the maximum positive effect onthe depletion is provided when the liquid storage portion is inverted,the maximum negative effect on the depletion is provided when the liquidstorage portion is upright and the minimum effect on the depletion isprovided when the liquid storage portion is horizontal.

The amount of liquid aerosol-forming substrate held in the liquidstorage portion may also affect the wicking rate. In other words, thegreater the amount of liquid aerosol-forming substrate held in theliquid storage portion, the greater the pressure that may be applied onthe one or more capillary wicks by the liquid aerosol-forming substrate,when the liquid storage portion is inverted.

The arrangement of the one or more capillary wicks relative to theliquid storage portion may also affect the wicking rate. When the liquidstorage portion is inverted, such that the one or more capillary wicksdraws liquid aerosol-forming substrate downwards, the wicking ratethrough the one or more capillary wicks may increase the closer the oneor more capillary wicks are arranged to the lowermost end of the liquidstorage portion. This may be because the pressure on the one or morecapillary wicks from volume of liquid aerosol-forming substrate abovethe one or more capillary wicks may increase. For example, the one ormore capillary wicks may be arranged towards an end of the liquidstorage portion. The one or more capillary wicks may be arranged at anend of the liquid storage portion. The liquid storage portion may have alength and the one or more capillary wicks may be arranged between anend of the liquid storage portion and about 30% of the length of theliquid storage portion away from an end. Where the one or more capillarywicks are arranged at an end of the liquid storage portion, 100% of theliquid storage portion may be arranged above the one or more capillarywicks when the liquid storage portion is inverted. Where the one or morecapillary wicks are arranged at about 30% of the length of the liquidstorage portion from an end of the liquid storage portion, 70% of theliquid storage portion may be arranged above the one or more capillarywicks when the liquid storage portion is inverted.

The electrical circuitry may be configured to calculate depletion basedon the relationship between one or more constant values determined in acalibration procedure and measurements of the orientation of the liquidstorage portion.

The electric circuitry may be arranged to supply a desired (or,alternatively predetermined) power to the aerosol generator. The aerosolgenerator may be activated on supply of the desired (or, alternativelypredetermined) power by the electric circuitry. The electric circuitrymay be configured to monitor the power supplied to the aerosolgenerator. The electric circuitry may also be configured to determinethe depletion of liquid aerosol-forming substrate based on the powersupplied to the aerosol generator. In other words, the electriccircuitry may be configured to determine the depletion of liquidaerosol-forming substrate based on measurements of the power supplied tothe aerosol generator and the orientation of the liquid storage portion.

The aerosol generator may comprise an electric heater comprising one ormore electric heating elements. The electric circuitry may be arrangedto sense the resistance of the one or more electric heating elements.The electric circuitry may be configured to ascertain the temperature ofthe one or more electric heating elements based on the measuredresistance. This configuration may be advantageous, as it does notrequire the electric circuitry to comprise a separate temperaturesensor, which may take up valuable space in the aerosol generatingsystem and may also be costly. The electrical resistance is used both asan ‘actuator’ (for the heating element) and a ‘sensor’ (temperaturemeasurement).

The electric circuitry may be arranged to measure the electricalresistance of the one or more electric heating elements. The electriccircuitry may be arranged to measure the electrical resistance of theone or more electric heating elements by measuring the current throughthe one or more electric heating elements and the voltage across the oneor more electric heating elements. The electric circuitry may beconfigured to determine the electrical resistance of the at least oneheating element from the measured current and voltage. The electriccircuitry may comprise a resistor, having a known resistance, in serieswith the at least one heating element and the electric circuitry may bearranged to measure the current through the at least one heating elementby measuring the voltage across the known-resistance resistor anddetermining the current through the at least one heating element fromthe measured voltage and the known resistance.

The electric circuitry may be configured to monitor activation of theelectric heater by monitoring the resistance of the one or more heatingelements over time. The electric circuitry may be configured todetermine the depletion of liquid aerosol-forming substrate based on themeasurements of resistance of the one or more electric heating elementsand the orientation of the liquid storage portion. The electriccircuitry may be configured to ascertain the temperature of the one ormore electric heating elements from the measurements of electricalresistance. If the one or more heating elements have suitablecharacteristics, such as a suitable temperature coefficient ofresistance, the temperature of the one or more heating elements may beascertained from measurements of the electrical resistance of the one ormore heating elements. The electric circuitry may be configured todetermine the depletion of liquid aerosol-forming substrate based on theascertained temperature of the one or more heating elements and theorientation of the liquid storage portion.

The electrically operated aerosol-generating system may comprise atemperature sensor arranged to sense the temperature of the one or moreelectric heating elements. The electric circuitry may be configured tomonitor activation of the electric heater by monitoring a temperature ofthe one or more heating elements, as sensed by the temperature sensor,over time. The electric circuitry may be configured to determine thedepletion of liquid aerosol-forming substrate based on measurements ofthe temperature of the one or more electric heating elements. Theelectric circuitry may be configured to determine the depletion ofliquid aerosol-forming substrate the temperature of the one or moreelectric heating elements and based on the orientation of the liquidstorage portion.

The electric circuitry may be arranged to determine depletion of liquidaerosol-forming substrate heated by the heater by monitoring an increasein the sensed or ascertained temperature over successive heating cyclesas the liquid aerosol-forming substrate in the liquid storage portion isdepleted. The electric circuitry may be configured to determinedepletion of liquid aerosol-forming substrate heated by the heater bymonitoring the rate of increase of the sensed or ascertained temperatureof the one or more heating elements over a portion of each heatingcycle, over successive heating cycles as the liquid aerosol-formingsubstrate in the liquid storage portion is depleted. The electriccircuitry may be arranged to determine depletion of liquidaerosol-forming substrate heated by the heater by monitoring an increasein the value of an integral over time of the sensed or ascertainedtemperature of the one or more heating elements over a portion of eachheating cycle, over successive heating cycles as the liquidaerosol-forming substrate in the liquid storage portion is depleted.

The electric circuitry may be configured to limit the temperature of theheating element to a maximum temperature. The electric circuitry may beconfigured to determine depletion of aerosol-forming substrate heated bythe heater by monitoring an amount of power applied to the heatingelement to maintain the maximum temperature.

The electric circuitry may be configured to determine the depletion ofliquid aerosol-forming substrate based on the orientation of the liquidstorage portion and a relationship between the power supplied to the oneor more electric heating elements and a resistance or temperature changeof the one or more electric heating elements.

If the amount of liquid aerosol-forming substrate has decreased below athreshold amount, for example if the liquid storage portion is empty ornearly empty, insufficient liquid aerosol-forming substrate may besupplied to the heater. This may result in the temperature of theheating element increasing. The temperature of the heating element, assensed by the temperature sensor, or the resistance of the one or moreelectric heating elements may enable the electric circuitry to determinethat the amount of liquid aerosol-forming substrate held in the liquidstorage portion has decreased to a desired (or, alternativelypredetermined) threshold.

The electric circuitry may be configured to determine an amount ofliquid aerosol-forming substrate in the liquid storage portion. Thedetermined amount of liquid aerosol-forming substrate held in the liquidstorage portion may be an absolute amount or a relative amount, e.g. apercentage value, or may be a determination that there is more or lessthan a threshold amount of liquid aerosol-forming substrate in theliquid storage portion.

The electric circuitry may be configured to determine an estimate of theamount of liquid aerosol-forming substrate remaining in the liquidstorage portion based on the determined depletion of liquidaerosol-forming substrate. The electric circuitry may be configured todetermine an estimate of the amount of liquid aerosol-forming substrateheld in the liquid storage portion by determining the depletion ofliquid aerosol-forming substrate and subtracting the depleted amountfrom a known initial amount to provide the estimate of liquidaerosol-forming substrate remaining in the liquid storage portion.

The electric circuitry may comprise a sensor for detecting the presenceof a liquid storage portion. The sensor may be configured to distinguishone liquid storage portion from another liquid storage portion and henceascertain how much liquid aerosol-forming substrate is contained in theliquid storage portion when full. The sensor may also be configured todetermine the composition of the liquid in the liquid storage portion.The sensor may be configured to determine the composition of the liquidin the liquid storage portion based on indicia on the liquid storageportion or the shape or size of the liquid storage portion. In use, theelectric circuitry may be configured to determine the depletion ofliquid aerosol-forming substrate based on the orientation of the liquidstorage portion, the composition of the liquid aerosol-formingsubstrate, and the monitored activation of the aerosol generator.

The aerosol-generating system may comprise indicator(s) for indicatingdetermined depletion information. For example, the aerosol-generatingsystem may comprise visual indicator(s), such as a display or an arrayof LEDs. For example, the aerosol generator may comprise audibleindicator(s), such as a buzzer or a loudspeaker. The electric circuitrymay be configured to indicate the determined depletion information. Forexample, the electric circuitry may be configured to display determineddepletion information on a display.

The aerosol-generating system may comprise electric circuitry configuredto control activation of the aerosol generator. The aerosol-generatingsystem may comprise electric circuitry configured to supply power to theaerosol generator. The electrical circuitry configured to supply powerto the aerosol generator may be the electrical circuitry configured todetermine the depletion of liquid aerosol-forming substrate held in theliquid storage portion.

The electric circuitry may comprise a sensor or a puff detector todetect air flow indicative of a puff being taken. The electric circuitrymay be arranged to provide an electric current pulse to the aerosolgenerator at a desired (or, alternatively predetermined) power when thesensor senses an operator taking a puff. The time-period of the electriccurrent pulse may be pre-set, depending on the amount of liquid desiredto be atomised. The electric circuitry may be programmable for thispurpose. The electric circuitry may be configured to monitor the totaltime of the time-periods of the electric current pulses to the aerosolgenerator. The electric circuitry may also be configured to estimatewhen the amount of liquid aerosol-forming substrate held in the liquidstorage portion will be depleted.

The liquid storage portion may be any suitable shape and size. Forexample, the liquid storage portion may be substantially cylindrical.The cross-section of the liquid storage portion may, for example, besubstantially circular, elliptical, square or rectangular.

The liquid storage portion may comprise a housing. The housing maycomprise a base and one or more sidewalls extending from the base. Thebase and the one or more sidewalls may be integrally formed. The baseand one or more sidewalls may be distinct elements that are attached orsecured to each other. The housing may be a rigid housing. As usedherein, the term ‘rigid housing’ is used to mean a housing that isself-supporting. The rigid housing of the liquid storage portion mayprovide mechanical support to the aerosol generator. The liquid storageportion may comprise one or more flexible walls. The flexible walls maybe configured to adapt to the volume of the liquid aerosol-formingsubstrate held in the liquid storage portion. The housing of the liquidstorage portion may comprise any suitable material. The liquid storageportion may comprise substantially fluid impermeable material. Thehousing of the liquid storage portion may comprise a transparent or atranslucent portion, such that liquid aerosol-forming substrate held inthe liquid storage portion may be visible to an operator through thehousing.

The liquid storage portion may be substantially sealed. The liquidstorage portion may comprise one or more outlets for liquidaerosol-forming substrate held in the liquid storage portion to flowfrom the liquid storage portion to the aerosol generator. The liquidstorage portion may comprise one or more semi-open inlets. This mayenable ambient air to enter the liquid storage portion. The one or moresemi-open inlets may be semi-permeable membranes or one way valves,permeable to allow ambient air into the liquid storage portion andimpermeable to substantially prevent air and liquid inside the liquidstorage portion from leaving the liquid storage portion. The one or moresemi-open inlets may enable air to pass into the liquid storage portionunder specific conditions.

The liquid aerosol-forming substrate held in the liquid storage portionmay be protected from ambient air. In some embodiments, ambient lightmay not be able to enter the liquid storage portion, so that the risk ofdegradation of the liquid is avoided. This may also enable a high levelof hygiene to be maintained. If the liquid storage portion is notrefillable, the liquid storage portion may have to be replaced by aoperator when the liquid aerosol-forming substrate held in the liquidstorage portion has been used up or has decreased to a desired (or,alternatively predetermined) threshold. During such replacement, it maybe desirable to prevent contamination of the operator with the liquidaerosol-forming substrate. If the liquid storage portion is refillable,the liquid storage portion may be refilled when the amount of liquidaerosol-forming substrate held in the liquid storage portion hasdecreased to a desired (or, alternatively predetermined) threshold. Theliquid storage portion may be arranged to hold sufficient liquidaerosol-forming substrate for a pre-determined number of puffs orheating cycles.

One or more capillary wicks are arranged to transfer liquidaerosol-forming substrate from the liquid storage portion to the aerosolgenerator. The one or more capillary wicks may comprise a capillarymaterial. A capillary material is a material that actively conveysliquid from one end of the material to another.

The structure of the capillary material may comprise a plurality ofsmall bores or tubes, through which the liquid can be transported bycapillary action. The capillary material may have a fibrous structure.The capillary material may have a spongy structure. The capillarymaterial may comprise a bundle of capillaries. The capillary materialmay comprise a plurality of fibres. The capillary material may comprisea plurality of threads. The capillary material may comprise fine boretubes. The fibres, threads or fine-bore tubes may be generally alignedto convey liquid to the aerosol generator. The capillary material maycomprise a combination of fibres, threads and fine-bore tubes. Thecapillary material may comprise sponge-like material. The capillarymaterial may comprise foam-like material.

The capillary material may comprise any suitable material or combinationof materials. Examples of suitable materials are a sponge or foammaterial, ceramic- or graphite-based materials in the form of fibres orsintered powders, foamed metal or plastics materials, a fibrousmaterial, for example made of spun or extruded fibres, such as celluloseacetate, polyester, or bonded polyolefin, polyethylene, terylene orpolypropylene fibres, nylon fibres or ceramic. The capillary materialmay have any suitable capillarity and porosity so as to be used withdifferent liquid physical properties. The liquid aerosol-formingsubstrate has physical properties, including but not limited toviscosity, surface tension, density, thermal conductivity, boiling pointand atom pressure, which allow the liquid to be transported through thecapillary material by capillary action.

The one or more capillary wicks may be arranged to contact liquid heldin the liquid storage portion. The one or more capillary wicks mayextend into the liquid storage portion. In this case, in use, liquid maybe transferred from the liquid storage portion to the aerosol generatorby capillary action in the one or more capillary wicks. The one or morecapillary wicks may have a first end and a second end. The first end mayextend into the liquid storage portion to draw liquid aerosol-formingsubstrate held in the liquid storage portion into the aerosol generator.The second end may extend into an air passage of the aerosol-generatingsystem. The second end may comprise one or more aerosol-generatingelements of the aerosol generator. The first end and the second end mayextend into the liquid storage portion. One or more aerosol-generatingelements of the aerosol generator may be arranged at a central portionof the wick between the first and second ends. In use, when the one ormore aerosol-generating elements are activated, the liquidaerosol-forming substrate in the one or more capillary wicks is atomisedat and around the one or more aerosol-generating elements.

The liquid aerosol-forming substrate may have physical properties,including viscosity, which allow the liquid to be transported throughthe one or more capillary wicks by capillary action.

The aerosol generator is arranged to receive liquid aerosol-formingsubstrate from the liquid storage portion via the one or more capillarywicks. The aerosol generator may be an atomiser. The aerosol generatormay comprise one or more aerosol-generating elements. The aerosolgenerator may be configured to atomise received liquid aerosol-formingsubstrate using heat. The aerosol generator may comprise a heater foratomising received liquid aerosol-forming substrate. The one or moreaerosol-generating elements may be heating elements. The aerosolgenerator may be configured to atomise received liquid aerosol-formingsubstrate using ultrasonic vibrations. The aerosol generator maycomprise an ultrasonic transducer. The one or more aerosol-generatingelements may comprise one or more vibratable elements.

The aerosol generator may comprise heater configured to heat theaerosol-forming substrate. The heater may comprise one or more heatingelements. The one or more heating elements may be arranged appropriatelyso as to most effectively heat received aerosol-forming substrate. Theone or more heating elements may be arranged to heat the aerosol-formingsubstrate primarily by means of conduction. The one or more heatingelements may be arranged substantially in directly contact with theaerosol-forming substrate. The one or more heating elements may bearranged to transfer heat to the aerosol-forming substrate via one ormore heat conductive elements. The one or more heating elements may bearranged to transfer heat to ambient air drawn through theaerosol-generating system during use, which may heat the aerosol-formingsubstrate by convection. The one or more heating elements may bearranged to heat the ambient air before it is drawn through theaerosol-forming substrate. The one or more heating elements may bearranged to heat the ambient air after it is drawn through theaerosol-forming substrate.

The heater may be electric heater or an electric heater. The electricheater may comprise one or more electric heating elements. The electricheater may comprise a single heating element. The electric heater maycomprise more than one heating element, for example two, or three, orfour, or five, or six or more heating elements. The one or more electricheating elements may comprise an electrically resistive material.Suitable electrically resistive materials may include: semiconductorssuch as doped ceramics, electrically “conductive” ceramics (such as, forexample, molybdenum disilicide), carbon, graphite, metals, metal alloysand composite materials made of a ceramic material and a metallicmaterial.

The one or more electric heating elements may take any suitable form.For example, the one or more electric heating elements may take the formof one or more heating blades. The one or more electric heating elementsmay take the form of a casing or substrate having differentelectro-conductive portions, or one or more electrically resistivemetallic tube.

The heater may comprise an inductive heater. Inductive heaters aredescribed in more detail below, in relation to the cartridge.

The aerosol generator may comprise one or more heating wires orfilaments encircling a portion of one or more capillary wicks. Theheating wire or filament may support the encircled portion of the one ormore capillary wicks.

The aerosol generator may comprise one or more vibratable elements andone or more actuators arranged to excite vibrations in the one or morevibratable elements. The one or more vibratable elements may comprise aplurality of passages through which aerosol-forming substrate may passand become atomised. The one or more actuators may comprise one or morepiezoelectric transducers.

The liquid storage portion may hold a supply of liquid aerosol-formingsubstrate. The liquid storage portion may comprise liquidaerosol-forming substrate held in the liquid storage portion. As usedherein, an aerosol-forming substrate is a substrate capable of releasingvolatile compounds that can form an aerosol. Volatile compounds may bereleased by heating the aerosol-forming substrate. Volatile compoundsmay be released by moving the aerosol-forming substrate through passagesof a vibratable element.

The aerosol-forming substrate may be liquid at room temperature. Theliquid aerosol-forming substrate may comprise both liquid and solidelements. The liquid aerosol-forming substrate may comprise nicotine.The nicotine containing liquid aerosol-forming substrate may be anicotine salt matrix. The liquid aerosol-forming substrate may compriseplant-based material. The liquid aerosol-forming substrate may comprisetobacco. The liquid aerosol-forming substrate may comprise atobacco-containing material containing volatile tobacco flavourcompounds, which are released from the aerosol-forming substrate uponheating. The liquid aerosol-forming substrate may comprise homogenisedtobacco material. The liquid aerosol-forming substrate may comprise anon-tobacco-containing material. The liquid aerosol-forming substratemay comprise homogenised plant-based material.

The liquid aerosol-forming substrate may comprise at least oneaerosol-former. An aerosol-former is any suitable known compound ormixture of compounds that, in use, facilitates formation of a dense andstable aerosol and that is substantially resistant to thermaldegradation at the temperature of operation of the system. Suitableaerosol-formers are well known in the art and include, but are notlimited to: polyhydric alcohols, such as triethylene glycol,1,3-butanediol and glycerine; esters of polyhydric alcohols, such asglycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- orpolycarboxylic acids, such as dimethyl dodecanedioate and dimethyltetradecanedioate. Aerosol formers may be polyhydric alcohols ormixtures thereof, such as triethylene glycol, 1,3-butanediol andglycerine. The liquid aerosol-forming substrate may comprise otheradditives and ingredients, such as flavourants.

The liquid aerosol-forming substrate may comprise water, solvents,ethanol, plant extracts and natural or artificial flavours. The liquidaerosol-forming substrate may comprise nicotine and at least one aerosolformer. The aerosol former may be glycerine. The aerosol-former may bepropylene glycol. The aerosol former may comprise both glycerine andpropylene glycol. The liquid aerosol-forming substrate may have anicotine concentration of between about 0.5% and about 10%.

A carrier material may be arranged in the liquid storage portion forholding the liquid aerosol-forming substrate. The carrier material maybe made from any suitable absorbent body of material, for example, afoamed metal or plastics material, polypropylene, terylene, nylon fibresor ceramic. The liquid aerosol-forming substrate may be retained in thecarrier material prior to use of the aerosol-generating system. Theliquid aerosol-forming substrate may be released into the carriermaterial during use. The liquid aerosol-forming substrate may bereleased into the carrier material immediately prior to use. Forexample, the liquid aerosol-forming substrate may be provided in acapsule. The shell of the capsule may melt upon heating by the heaterand releases the liquid aerosol-forming substrate into the carriermaterial. The capsule may contain a solid in combination with theliquid.

The aerosol-generating system may comprise one or more electric powersupplies. The power supply may be a battery. The battery may be aLithium based battery, for example a Lithium-Cobalt, aLithium-Iron-Phosphate, a Lithium Titanate or a Lithium-Polymer battery.The battery may be a Nickel-metal hydride battery or a Nickel cadmiumbattery. The power supply may be another form of charge storage devicesuch as a capacitor. The power supply may require recharging and beconfigured for many cycles of charge and discharge. The power supply mayhave a capacity that allows for the storage of enough energy for one ormore experiences; for example, the power supply may have sufficientcapacity to allow for the continuous generation of aerosol for a periodof around six minutes, corresponding to the typical time taken to smokea conventional cigarette, or for a period that is a multiple of sixminutes. In another example, the power supply may have sufficientcapacity to allow for a desired (or, alternatively predetermined) numberof puffs or discrete activations of the heater and actuator.

The aerosol-generating system may comprise a operator input, such as aswitch or button. This enables the operator to turn the system on. Theswitch or button may activate the aerosol generator. The switch orbutton may initiate aerosol generation. The switch or button may preparethe control electronics to await input from the puff detector.

The aerosol-generating system may comprise a housing. The housing may beelongate. The housing may comprise any suitable material or combinationof materials. Examples of suitable materials include metals, alloys,plastics or composite materials containing one or more of thosematerials, or thermoplastics that are suitable for food orpharmaceutical applications, for example polypropylene,polyetheretherketone (PEEK) and polyethylene. The material may be lightand non-brittle.

The housing may comprise a cavity for receiving the power supply. Thehousing may comprise a mouthpiece. The mouthpiece may comprise at leastone air inlet and at least one air outlet. The mouthpiece may comprisemore than one air inlet. One or more of the air inlets may reduce thetemperature of the aerosol before it is delivered to an operator and mayreduce the concentration of the aerosol before it is delivered to anoperator.

The aerosol-generating system may be portable. The aerosol-generatingsystem may have a size comparable to a conventional cigar or cigarette.The aerosol-generating system may have a total length between about 30mm and about 150 mm. The aerosol-generating system may have an externaldiameter between about 5 mm and about 30 mm.

The aerosol-generating system may comprise a mouthpiece portion. Themouthpiece portion may be configured to allow a puff or draw on themouthpiece portion to draw air through the atomising element past theaerosol generator.

The aerosol-generating system may have a housing. The housing maycomprise a connecting portion for connection with a main unit comprisinga power supply and control electronics. The connecting portion maycomprise a screw fitting, a push fitting or a bayonet fitting forexample.

The aerosol-generating system may comprise a main unit and a cartridge.The main unit comprises the control system. The cartridge comprises theliquid storage portion for holding the liquid aerosol-forming substrate.The main unit may be configured to removably receive the cartridge. Thetilt sensor may be arranged to sense the orientation of the liquidstorage portion when the cartridge is received by the main unit.

The main unit may comprise one or more power supplies. The main unit maycomprise the aerosol generator.

The cartridge may comprise the aerosol generator. Where the cartridgecomprises the aerosol generator, the cartridge may be referred to as a‘cartomizer’.

The aerosol-generating system may comprise an aerosol-generating elementcomprising the aerosol generator. The aerosol-generating element may beseparate of the main unit and the cartridge. The aerosol-generatingelement may be removably receivable by at least one of the main unit andthe cartridge.

The main unit may comprise the tilt sensor. The cartridge may comprisethe tilt sensor.

The aerosol generator may comprise a heater substantially as describedabove in relation to a previous embodiment. The heater may be aninductive heater, such that no electrical contacts are formed betweenthe cartridge and the main unit. The main unit may comprise an inductorcoil and a power supply configured to provide high frequency oscillatingcurrent to the inductor coil. The cartridge may comprise a susceptorelement positioned to heat the aerosol-forming substrate. As usedherein, a high frequency oscillating current means an oscillatingcurrent having a frequency of between 10 kHz and 20 MHz.

The cartridge may be removably coupled to the main unit. The cartridgemay be removed from the main unit when the aerosol-forming substrate hasbeen consumed. The cartridge is preferably disposable. However, thecartridge may be reusable and the cartridge may be refillable withliquid aerosol-forming substrate. The cartridge may be replaceable inthe main unit. The main unit may be reusable.

The cartridge may be manufactured at low cost, in a reliable andrepeatable fashion. As used herein, the term ‘removably coupled’ is usedto mean that the cartridge and the main unit can be coupled anduncoupled from one another without significantly damaging either themain unit or the cartridge.

The cartridge may have a simple design. The cartridge may have a housingwithin which a liquid aerosol-forming substrate is held. The cartridgehousing may be a rigid housing. The housing may comprise a material thatis impermeable to liquid.

The main unit may have a housing. The housing may comprise a connectingportion for connection with the atomising element. The main unit housingmay have a connecting portion corresponding to the connecting portion ofthe housing of the atomising element. The connecting portion maycomprise a screw fitting, a push fitting or a bayonet fitting forexample.

The cartridge may comprise a lid. The lid may be peelable beforecoupling the cartridge to the main unit. The lid may be piercable.

The main unit may comprise a cavity for receiving the cartridge. Themain unit may comprise a cavity for receiving the power supply.

The main unit may comprise the aerosol generator. The main unit maycomprise one or more control systems of the aerosol-generating system.The main unit may comprise the power supply. The power supply may beremovably coupled to the main unit.

The main unit may comprise the mouthpiece. The mouthpiece may compriseat least one air inlet and at least one air outlet. The mouthpiece maycomprise more than one air inlet.

The main unit may comprise a piercing element for piercing the lid ofthe cartridge. The mouthpiece may comprise the piercing element. Themouthpiece may comprise at least one first conduit extending between theat least one air inlet and a distal end of the piercing element. Themouthpiece may comprise at least one second conduit extending between adistal end of the piercing element and the at least one air outlet. Themouthpiece may be arranged such that in use, when the mouthpiece isdrawn upon, air flows along an air passage extending from the at leastone air inlet, through the at least one first conduit, through a portionof the cartridge, through the at least one second conduit and exits theat least one outlet. This may improve airflow through the main unit andenable the aerosol to be delivered to the operator more easily.

In use, a cartridge may be inserted as described herein into the cavityof a main unit as described herein. The mouthpiece may be attached tothe body of the main unit, which may pierce the cartridge with thepiercing portion. The main unit may be activated by pressing the switchor the button. Drawing upon the mouthpiece draws air into the main unitthrough the one or more air inlets. The air may pass over a puffdetector of the electrical circuitry and the electrical circuitry maydetect the airflow and activate the aerosol generator. The air may passover a portion of the activated aerosol generator, entraining atomisedaerosol-forming substrate, and exit the main unit through the air outletin the mouthpiece. On activation of the aerosol generator, theelectrical circuitry may measure the orientation of the liquid storageportion using the tilt sensor. The electrical circuitry may alsodetermine the depletion of liquid aerosol-forming substrate from theliquid storage portion based on the orientation measurements. Theelectric circuitry may also display the consumption on a display of themain unit, to indicate to the operator the depletion of liquidaerosol-forming substrate.

A kit of parts may be provided, comprising a cartridge and a main unit,substantially as described above. An aerosol-generating system accordingto the aspect of the present invention may be provided by assembling thecartridge and the main unit. The elements of the kit of parts may beremovably connected. The elements of the kit of parts may beinterchangeable. Elements of the kit of parts may be disposable.Elements of the kit of parts may be reusable.

In one embodiment, there is provided a main unit for an electricallyoperated aerosol-generating system according to a previous embodiment.The main unit comprises the electrical circuitry and the tilt sensor.The tilt sensor is arranged to sense the orientation of the liquidstorage portion when the cartridge is removably coupled to the mainunit. The main unit may further comprise the aerosol generator.

In another embodiment, there is provided a cartridge for an electricallyoperated aerosol-generating system according to a previous embodiment.The cartridge comprises the liquid storage portion and the tilt sensor.The cartridge may further comprise the aerosol generator.

A method of determining the depletion of liquid aerosol-formingsubstrate from a liquid storage portion of an aerosol-generating systemmay comprise: holding a liquid aerosol-forming substrate in a liquidstorage portion of an aerosol-generating system; arranging a tilt sensorto sense the orientation of the liquid storage portion; measuring theorientation of the liquid storage portion; and determining the depletionof liquid aerosol-forming substrate based on the orientation of theliquid storage portion.

The method may further comprise: determining a first estimate ofdepletion of liquid aerosol-forming substrate based on one or more of:the power supplied to the aerosol generator, the resistance ortemperature of the one or more electric heating elements, and arelationship between the power supplied to the one or more electricheating elements and a resulting resistance or temperature change of theone or more electric heating elements. The method may further comprise:determining a second estimate of depletion of liquid aerosol-formingsubstrate held in the liquid storage portion based on the firstdetermined estimate of depletion and the orientation of the liquidstorage portion as sensed by the tilt sensor.

FIG. 1 is a schematic illustration of an electrically operatedaerosol-generating system 100. The system 100 comprises a main unit 101and a cartridge 200. The main unit 101 comprises a battery 110 andelectrical circuitry 120. The cartridge 200 comprises a liquid storageportion 210 and an aerosol generator 220. Since the cartridge 200comprises the aerosol generator 220, the cartridge 200 may be referredto as a ‘cartomizer’.

The liquid storage portion 210 is substantially circularly cylindricaland is configured to hold a liquid aerosol-forming substrate 230 in acarrier material. An airflow passage 240 passes through the centre ofthe liquid storage portion 210 such that the liquid storage portion 210forms an annular, circularly cylindrical volume. A capillary wick 250extends across the airflow passage 240, between opposite sides of theliquid storage portion 210. The capillary wick 250 comprises a capillarymaterial that is arranged to draw liquid aerosol-forming substrate alongthe capillary wick 250 from either end. The capillary wick 250 isarranged towards the distal end of the liquid storage portion 200, closeto the mouthpiece 260.

As shown in FIG. 1, the aerosol generator 220 comprises an electricallypowered heater in the form of a heater filament that is coiled around acentral section of the capillary wick 250 within the airflow passage240. The heater is electrically connected to the battery 110 of the mainunit 101 via the electrical circuitry 120. Power is provided from thebattery 120 in main unit 101 to the heater 220 in the cartridge 200,under the control of the electrical circuitry 130. The capillary wick250 delivers liquid aerosol-forming substrate 230 from the liquidstorage portion 210 to the aerosol generator 220.

The cartridge 200 also comprises a mouthpiece 260 arranged at an end ofthe airflow passage 240. The mouthpiece 260 comprises an air outlet (notshown) to draw air through the airflow passage 240.

A tilt sensor 270 is arranged in the main unit 301. The tilt sensor 270is arranged to sense the orientation of the liquid storage portion 210of the cartridge 200, when the cartridge 200 is received by the mainunit 101.

The system 100 illustrated in FIG. 1 operates as follows. When air isdrawn through the mouthpiece 260 of the cartridge 200, air is drawn intothe airflow passage 230 through inlet holes (not shown) in the housingof the main unit 101 and the cartridge 200. An airflow sensor, such as amicrophone (not shown), is provided in the electrical circuitry 120 andsenses the flow of air induced by the draw on the mouthpiece 260. When asufficient airflow is detected, the electrical circuitry 120 suppliespower to the aerosol generator 220 from the battery 120. This activatesthe heater, causing the heater filament to heat up and vaporise liquidaerosol-forming substrate 230 held in the central section of thecapillary wick 250 in the immediate vicinity of the heater filament. Theresulting vapour is released in the airflow passage 240 and is cooled inthe air flowing through the passage, past the aerosol generator. Thecooled vapour condenses to form an aerosol. The aerosol is drawn in theairflow flowing through the airflow passage 240 and out the mouthpiece260. When the mouthpiece is no longer drawn upon, and the airflow pastthe airflow sensor drops below a threshold level, the electricalcircuitry 120 stops providing power to the aerosol generator 220. Thecapillary wick 250 is replenished with liquid aerosol-forming substrate230 from the liquid storage portion 210 by capillary action.

In use, the electric circuitry 120, 320 periodically measures theorientation of the liquid storage portion 210 and determines thedepletion of liquid aerosol-forming substrate based on the measurementsof the orientation of the liquid storage portion 210.

In some embodiments, the electric circuitry 120 comprises a memory (notshown) storing a lookup table. The lookup table comprises referenceorientation information associated with depletion information. In theseembodiments, the electric circuitry compares the measurements oforientation with the reference orientation information stored in thelookup table. On determining a match between a measurement oforientation and a reference orientation, the electric circuitrydetermines the depletion information associated with the matchedreference orientation information in the lookup table. As such, theelectric circuitry determines the depletion of liquid aerosol-formingsubstrate 230 from the liquid storage portion 210.

The main unit 101, 301 may also comprise a display (not shown). Theelectric circuitry may send the associated depletion information to thedisplay to indicate the depletion of liquid aerosol-forming substrate230 from the liquid storage portion 210.

It will be appreciated that in some embodiments, the electric circuitrywill be configured to calculate the depletion of liquid aerosol-formingsubstrate based on measurements of orientation of the liquid storageportion. For example, FIG. 2 shows the liquid storage portion 200 heldinverted, at an angle α to the vertical axis A-A. The orientation of theliquid storage portion 200 may be considered to be the angle α betweenthe longitudinal axis of the liquid storage portion and the verticalaxis A-A. A rate of depletion or an amount of liquid aerosol-formingsubstrate depleted from the liquid storage portion may be calculated asshown in Equation 1.

D _(D) =D _(C) cos α   Equation 1

The determined depletion D_(D), either a determined rate of depletion ora determined amount of depletion, may be calculated from the product ofa depletion constant D_(C) and the cosine of the orientation angle α.The depletion constant D_(C) may be determined from a calibrationprocedure or from calculations using the known properties of the one ormore capillary wicks and the liquid aerosol-forming substrate.

It will be appreciated that the depletion may be a function of severalvariables. As such, the total depletion may comprise several aspects,one of which is the determined depletion D_(D) related to the tilt ofthe liquid storage portion, as shown in Equation 1. Depletions may alsobe determined for other aspects of the depletion, which may depend onvariables such as the temperature of the liquid aerosol-formingsubstrate and the power supplied to the aerosol generator. An estimatefor the total depletion may be determined from a combination of thedetermined depletions for each of the aspects.

In some embodiments, the electric circuitry 120 is further configured todetermine one or more of the amount of liquid aerosol-forming substrate230 remaining in the liquid storage portion 210 and the time or numberof puffs remaining based on the measurements of the orientation of theliquid storage portion 210. The electric circuitry 120 may also displayon the display the determined amount of liquid aerosol-forming substrate230 remaining in the liquid storage portion 210 and the time or numberof puffs remaining.

In some embodiments, the electric circuitry is configured to measureother quantities of the aerosol-generating system.

For example, the electric circuitry 120 may be configured to measure thepower supplied to the aerosol generator. In this embodiment, theelectric circuitry is configured to determine a first estimate ofdepletion of liquid aerosol-forming substrate based on the measurementsof the power supplied to the aerosol generator. Furthermore, in thisembodiment, the depletion information stored in the lookup table andassociated with the reference orientation information comprises amultiplier for adjusting the first estimate of depletion. As such, theelectric circuitry multiplies the first estimate of depletion with themultiplier determined from measurements of the orientation of the liquidstorage portion. The electric circuitry then determines a secondestimate of depletion of liquid aerosol-forming substrate from theliquid storage portion based on the product of the first estimate ofdepletion and the multiplier. The electric circuitry may send the secondestimate of depletion to the display to inform the operator of thedepletion.

It will be appreciated that the examples described herein arestraightforward examples, and that modifications may be made to theillustrated circuits to provide different or more sophisticatedfunctionality.

1. An electrically operated aerosol-generating system for receiving aliquid aerosol-forming substrate, the aerosol-generating systemcomprising: a liquid storage portion configured to hold a liquidaerosol-forming substrate; an aerosol generator configured to receiveliquid aerosol-forming substrate from the liquid storage portion; one ormore capillary wicks configured to transfer liquid aerosol-formingsubstrate from the liquid storage portion to the aerosol generator; atilt sensor configured to sense the orientation of the liquid storageportion; and electric circuitry configured to monitor the orientation ofthe liquid storage portion as sensed by the tilt sensor and determinedepletion of liquid aerosol-forming substrate based on the orientationof the liquid storage portion.
 2. The electrically operatedaerosol-generating system according to claim 1, wherein the one or morecapillary wicks are arranged towards an end of the liquid storageportion.
 3. The electrically operated aerosol-generating systemaccording to claim 1, wherein the electric circuitry is configured todetermine an amount of liquid aerosol-forming substrate depleted fromthe liquid storage portion or a rate of depletion of liquidaerosol-forming substrate from the liquid storage portion.
 4. Theelectrically operated aerosol generating system according to claim 1,wherein: the electric circuitry is arranged to supply a desired power tothe aerosol generator; and determine the depletion of liquidaerosol-forming substrate based on the orientation of the liquid storageportion and the power supplied to the aerosol generator.
 5. Theelectrically operated aerosol-generating system according to claim 1,wherein the aerosol generator comprises an electric heater comprisingone or more electric heating elements.
 6. The electrically operatedaerosol-generating system according to claim 5, wherein the electriccircuitry is arranged to measure the resistance of the one or moreelectric heating elements.
 7. The electrically operatedaerosol-generating system according to claim 5, wherein theaerosol-generating system comprises a temperature sensor arranged tosense temperature of the one or more electric heating elements.
 8. Theelectrically operated aerosol generating system according to claim 7,wherein the electric circuitry is configured to: monitor activation ofthe electric heater by monitoring the resistance or the temperature ofthe one or more heating elements over time; and determine the depletionof liquid aerosol-forming substrate based on the orientation of theliquid storage portion and the resistance or the temperature of the oneor more electric heating elements.
 9. The electrically operated aerosolgenerating system according to claim 8, wherein the electric circuitryis configured to determine the depletion of liquid aerosol-formingsubstrate based on the orientation of the liquid storage portion and arelationship between the power supplied to the one or more electricheating elements and a resistance change or temperature change of theone or more electric heating elements.
 10. The electrically operatedaerosol generating system according to claim 7, wherein the electriccircuitry is further configured to: determine a first estimate ofdepletion of liquid aerosol-forming substrate based on one or more of:the power supplied to the aerosol generator, the resistance or thetemperature of the one or more electric heating elements, and arelationship between the power supplied to the one or more electricheating elements and a resistance change or temperature change of theone or more electric heating elements; and determine a second estimateof depletion of liquid aerosol-forming substrate held in the liquidstorage portion based on the first determined estimate of depletion andthe orientation of the liquid storage portion as sensed by the tiltsensor.
 11. The electrically operated aerosol-generating systemaccording to claim 1, wherein the electric circuitry is configured todetermine an estimate of the amount of liquid aerosol-forming substrateremaining in the liquid storage portion based on the determineddepletion of liquid aerosol-forming substrate.
 12. The electricallyoperated aerosol-generating system according to claim 11, wherein theelectric circuitry is configured to determine the estimate of the amountof liquid aerosol-forming substrate held in the liquid storage portionby subtracting the determined depletion of liquid aerosol-formingsubstrate from a known initial amount to provide the estimate of liquidaerosol-forming substrate remaining in the liquid storage portion. 13.The electrically operated aerosol-generating system according to claim1, wherein the aerosol-generating system comprises a main unit and acartridge and wherein the main unit comprises a power supply and theelectric circuitry and the cartridge comprises the liquid storageportion.
 14. The electrically operated aerosol-generating systemaccording to claim 13, wherein the main unit further comprises the tiltsensor arranged to sense the orientation of the liquid storage portionwhen the cartridge is removably received by the main unit.
 15. Theelectrically operated aerosol-generating system according to claim 13,wherein the cartridge further comprises the tilt sensor arranged tosense the orientation of the liquid storage portion.